1. Field
The present invention relates to pool safety valves that bleed air into the pool""s drain line to relieve excessively high vacuum levels causing the pool""s pump to lose prime and more particularly to such valves that include provisional to adjust on site the trip level at which air is bled into the pool""s drain line.
2. Prior Art
There have been numerous cases of serious injuries and deaths caused by high vacuum levels at a pool""s drain port which holds an individual to the drain port and in some cases causes disembowelment. When such an incident occurs, the vacuum level in the drain line leading from the drain port to the pool""s pump rises sharply.
Various safety valves have been developed in which the high vacuum level occurring during such incidents is sensed and used to trip the valve and allow air to bleed into the drain line, causing the pump to lose prime. Although such valves function to some degree, they generally exhibit two problems. The first is they are often set at the factory to a predetermined trip level which does not always correspond to an appropriate level for a particular pool. Variations in pumps, pipe diameters, pipe length and the number of turns and pitches in a pipe line, all affect the vacuum level at which a safety valve""s trip level should be set. This setting is best done at the pool site.
The second problem is related to the valve""s reliability. Virtually all valves include gaskets which must remain sealed if the valve is to function properly. If a gasket becomes dislodged from its seat, it can allow air to leak around the closure elements of the valve, causing the pump to lose prime when there is no emergency. This effectively shuts down the pool and can only be remedied by removing the valve and having it repaired, which often requires the valve to be returned to the factory.
A safety valve is needed which can be easily adjusted in the field by a service technician to a trip level that is appropriate for each site. For improved reliability, a safety valve is needed that overcomes the leakage past gaskets that often occurs because the gasket becomes unseated. These needed improvements are provided by the valve of the present invention described in the following sections.